I ordered a book from Amazon yesterday morning. A few hours later I’m sitting at my computer and there is a knock at the door. I open the door and this girl is standing there and she says "Are you Alex Tabarrok?" I say yes and she hands me the book. My jaw just about hits the floor. I’m totally confused. The girl runs away laughing. Only later do I figure it out. I ordered from Amazon Marketplace. The seller just happened to live nearby and she brought the book over. Pretty cool.